Biological invasions are a form of global change threatening biodiversity, ecosystem stability, and human health, and cost government agencies billions of dollars in remediation and eradication programs. Attempts to eradicate introduced species are most successful when detection of newly established populations occurs early in the invasion process. We review existing and emerging tools -specifically environmental DNA (eDNA), chemical approaches, remote sensing, citizen science, and agency-based monitoring -for surveillance and monitoring of invasive species. For each tool, we consider the benefits provided, examine challenges and limitations, discuss data sharing and integration, and suggest best practice implementations for the early detection of invasive species. Programs that promote public participation in large-scale biodiversity identification and monitoring (such as iNaturalist and eBird) may be the best resources for early detection. However, data from these platforms must be monitored and used by agencies that can mount appropriate response efforts. Control efforts are more likely to succeed when they are focused on early detection and prevention, thereby saving considerable time and resources.

1. Invasive plant populations respond positively to light increase from windstormcaused canopy damage, but are typically out-competed over time as the tree canopy recovers. Some invasive plants have the ability to slow or even completely prevent canopy regrowth. It is important to understand invasive plant dynamics in windstorm blowdowns to inform effective forest management. We hypothesized that blowdown areas are more invaded than unaffected forest and that invadedness of a blowdown will decrease with increasing time since disturbance and increase with disturbance magnitude.2. We used Landsat imagery to identify 31 blowdowns caused by one of three storms in southern Illinois of the United States: 2006 tornado, 2009 derecho or 2017 tornado. We statistically matched these blowdowns to areas of unaffected forest based on slope, aspect, elevation, distance to a road and distance to a trail.We surveyed blowdown and unaffected units for invasive plants in summer 2018.Disturbance magnitude was measured in two ways: per cent change in normalized difference vegetation index (NDVI) and area of blowdown.3. Overall, blowdowns were more invaded than their statistically matched areas.Invadedness of blowdowns decreased with increasing time since disturbance, indicating that the blowdowns are recovering as tree canopy regrowth shades out invasive plants. Per cent change in NDVI was not a supported predictor of blowdown invadedness, but invadedness was strongly positively related to blowdown size. Larger blowdowns recover more slowly than smaller disturbances due to different recovery pathways, providing more time and opportunity for the spread and establishment of invasive plants. Synthesis.Our findings suggest that although blowdowns contained higher cover of invasive plants than forest unaffected by windstorms, invasive plants were responding negatively to canopy regrowth. Land managers should prioritize treatment of invasive plants in larger and more recent blowdowns. K E Y W O R D S blowdown, canopy disturbance, derecho, Elaeagnus umbellata, Illinois, Landsat, Lonicera japonica, tornado S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section at the end of the article. How to cite this article: Daniels MK, Larson ER. Effects of forest windstorm disturbance on invasive plants in protected areas of southern Illinois, USA.

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